[1] Assington is located on the south side of Forest Street in rural eastern Sherborn, between the Rocky Narrows Reservation and Farm Road.

The estate is set on 30 acres (12 ha) of mostly woods, with a winding drive leading south from the road to the main house.

The main block is 7 bays wide, with an enclosed and pedimented entry that is flanked by sidelight windows and topped by a fanlight.

The south facade faces the river, and has a bowed central section that rises to interrupt the roof's balustrade.

[2] Assington was built in 1929–1930 for George and Muriel Saltonstall Lewis, to designs by architect William Truman Aldrich (1880–1966).